Core clamp



H. EPSTEIN CORE CLAMP June 7, 1949.

Original Filed Dec. 11, 1944 FIG.- 1

F I G. 2

MIN

FIG. 3

INVENTOR. HIRSCH EPSTEIN BY I Attorney Patented June 7, i949 UNITED STATES PATENT OFFlCE CORE CLAMP Hirsch Epstein, Chicago, Ill., assignor, by direct and mesne assignments, to Advance Transformer 00., Chicago, Ill., a corporation of Illinois Original application December 11, 1944, Serial No. 567,542. Divided and this application October 1, 1945, Serial No. 619,512

1 Claim. (01. 175--356) l 2 This application is a division of my pending Figure 2 is a view taken along the line 2-2 application, Serial No. 567,542, filed December of. Figure 1 and looking in the direction of the 11, 1944. arrows; and

The present invention relates to transformers Figure 3 is a view taken along the line 3-3 or reactors, particularly such as are used in con- 'of Figure 1 and looking in the direction of the nection with alternating current hot cathode arrows.

fluorescent lighting devices. In the drawing I have shown the principles of It is one of the objects of the present inventhe present invention as applied to areactor such tion to provide a transformer or reactor for the as used in alternating current fluorescent lightabove mentioned purposes which will be silent in ing circuits. This reactor comprises a Single operation, coil c wound on a spool I of paper, cardboard The core of transformers of the type here inor the like, and in which is assembled a core convolved consists of two stacks of laminations, prefsisting of two identical stacks 23 of thin,

erably but not necessarily E-shaped, which are shaped, silicon steel laminations.

placed in abutment to make an almost closed, but Each lamination includes an end portion 4 from not completely closed, magnetic circuit, a small which proj Outer legs 5 d 5 and a n r magnetic gap or space being left between the two leg I. The stacks 23 of laminations are ascores. Generally the two core parts are fitted sembled in a manner such that there is slight into one or more coils, which are the coils of the gap 8 between the central legs I of the two stacks transformer or reactor. In order to obtain proper 0 and a corresponding gap 9 between the legs 55 electrical functioning of a structure of this type and between the legs 6-6. These gaps may be it is necessary that the air gap be of a constant filled by thin paper spacers. A wooden wedge ID value. A piece of non-magnetic material, such is forced through the core between the legs I as paper or the like, is positioned between the two and the tube III to hold the coil tightly on the core structures to maintain the necessary mini- 5 cores.

mum spacing between them. It has been found In order to hold the two stacks of laminations that there is a tendency for the two core strucagainst vibrating towards and from one another tures to separate from one another and thus inwhen a cycle or 60 cycle current flows through crease the air gap between them, unless means the coil there is provided a pair of identical is provided to prevent such separation. It is one clamps 4 n pp i e id s f the react rof the objects of the present invention to provide Each clamp is, optionally, spaced from the core a simple clamp structure for holding the two core by a sheet of paper ii. The clamps are made of parts together against separation. soft steel or iron which is dead, that is, substan- I have found that the end laminations of a tially devoid of springiness. The clamps are core of the above mentioned type are primarily 3,5 placed on the reactors and then the arms l8--l8 responsible for the objectionable transformer of the clamps are pressed together as by means noises. It. is one of the objects of the present of a pneumatic or hand press. Each clamp invention to provid a simple type of clam for l3--l4 may, if desired, have a pair of ears 20 conholding the outermost laminations against vibrastituting clamping jaws on opposite sides theretion. 0 of which ears fold down and embrace the free It is a still further object of the present invenends of adjacent outer legs 5 or 6 as the case tion to provide a simple clamp which will permay be. These ears are preferably, although not form the function of preventing vibration of the necessarily, separated from the core structure by end laminations and also perform the function of the paper sheet ii. The ears 2020 of each preventing separation of the two core structures. clamp are pressed together in firm pressure en- The attainment of the above and further obgagement with the reactor by the exertion of a jects of the present invention will be apparent great pressure thereon in a pneumatic or hand from the following specification taken in conpress. The clamps ll-ll not only prevent vijunction with the accompanying drawing formbration of the adjacent free ends of the legs 55 ingapart thereof. and 68 but also prevent the core structures Inthe drawing: 23 from rocking or vibrating towards and from Figure 1 is a top view of a reactor embodying one another under the magnetic action to which the present invention, parts of the reactor being the structure is subjected. broken away to illustrate the interior construc- The assembled reactor is varnished with an tion; insulating varnish and placed in a casing and a 3 completely encased by an insulating compound, such as tar, within the casing, as is usual in the art.

I have found that as a result of the clamping arrangement herein disclosed the magnetic structures are exceedingly quiet in. their action where otherwise they would be quite noisy. The clamps are simple and economical of construction and easily positioned on the magnetic structure.

In compliance with the requirements of the patent statutes I have here shown and described a preferred embodiment of my invention. It is, however, to be understood that the invention is not limited to the precise construction here shown, the same being merely illustrative of the principles of the invention. What I consider new and desire to secure by Letters Patent'is:

In an alternating current magnetic apparatus, a magnetic core comprising two separate stacks of assembled laminations together forming a central leg and two outer legs joined by end portions, there being a non-magnetic gap between the two stacks at the middle or the outer legs of the assembly, means surrounding the central leg for setting up an alternating magnetic flux in said core, each outer leg having a. clamp of metal that is substantially devoid of springiness, each clamp including a clamp body extending across the stacks of laminations and lengthwise of an outer leg of the core, each clamp body having at opposite ends thereof arms pressing the two stacks of laminations towards one another and said lengthwise extending clamp body having clamping jaws at the opposite longitudinal 4 edges thereof and at the non-magnetic gaps of the core, said jaws being bent from the clamp body to a position extending over one oi! the nonmagnetic gaps between the stacks and overlying the portions 0! the outer-laminations adjacent the non-magnetic gap and firmly clamping said portions of the laminations together thereby holding said portions against vibration, each jaw being 01' substantially greater width along its line of bend from the clamp body than it is at the pressure engaging jaw end remote from the clamp body, the maximum length oi each jaw in a direction lengthwise of the member over which it extends being substantially less than the minimum distance from the jaw to an adjacent arm of the clamp.

HIRSCH EPSTEIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,512,032 Ledwinka Oct. 21, 1924 1,627,493 Dubilier May 3, 1927 1,628,398 Casper et al May 10, 1927 1,629,132 Thordarson May 17, 1927 1,666,661 Morton Apr. 17, 1928 1,690,154 Alden Nov. 6, 1928 DB, -.-----L-- Aug- 27, 2,064,772 Vogt Dec. 15, 1936 2,068,320 Grant Jan. 19, 1937 

